US 2011/0095620 A1=DE 10 2007 034 750 A1 discloses an improved galvanic isolator with an inductive transducer in a layer structure. On the upper and lower surfaces of a substrate plate which forms a barrier layer having a sufficient thickness and sufficient insulation characteristics, conductive traces are provided to define coil windings which are protected by insulating cover layers which partially have feeding conductive traces extending thereon which, in a first embodiment, are connected to a transmitter chip or a receiver chip through vias. The vias extend through the insulating cover layers and partly through the substrate plate as well. The coil windings form the inductive transducer which, in a second embodiment, is connected to the transmitter chip and the receiver chip by wire connections. Thus, the chips with the electrical or electronic components are arranged outside the galvanic isolator.
A broadband radio-frequency transformer having a layer structure is known from U.S. Pat. No. 5,015,972, wherein primary and secondary windings are arranged between dielectric layers which in turn are located between ferrite cover plates. Electrical or electronic components are not included in the layer structure.
An energy supply unit for transmitting auxiliary energy is known from EP 1 310 036 B1 and comprises primary and secondary coils provided on carrier plates with an air gap therebetween. In order to extend the clearance distance between the coils, an insulating plate is disposed in the air gap which protrudes beyond the carrier plates. A layer structure of a printed circuit board is not formed in this manner.
In some electrical/electronic devices high voltages have to be handled, and for protecting against overvoltages a galvanic isolation is often provided between individual electric circuits or potential groups within the device. In order to avoid electrical flashovers in the devices, specific clearance and creepage distances for discharge currents must be kept between the electric circuits to be separated, or an insulating material of a predetermined quality and minimum thickness has to be placed between the electric circuits. Thus, there is a galvanic isolation distance between the individual electric circuits, across which electrical energy is to be exchanged, which is useful for power supply or data exchange or information exchange. This electrical energy will be referred to as an electrical signal below.
Printed circuit boards, also referred to as circuit boards or PCBs, are often used as a carrier for electrical/electronic components, assemblies and conductive traces (referred to as “components” below). Printed circuit boards may be flexible or rigid and are available in a layer structure design. For galvanic isolation between different electric circuits or potential groups on the printed circuit board it has been known to provide a “trench” on the printed circuit board, across which no component extends. The width of the isolation trench corresponds to the minimum distance in air or the minimum creepage distance along the surface of the isolation trench, which must be kept in order to achieve sufficient electrical voltage protection. The wider the isolation trench is selected on the printed circuit board, the less usable area is available for accommodating electrical/electronic components.
For signal exchange, galvanically isolated electric circuits are coupled with each other by coupling components, and for this purpose inductive and capacitive transformers or antenna systems operating in the electromagnetic near field are useful, each comprising a first and at least a second coupling element between which a solid insulating material extends. The dielectric strength of this insulating material determines the tolerable voltage difference between the potential groups or individual electric circuits.